There is an existing need to find a composition which induces a high prebiotic effect all along the colon (i.e. up to the descending part of the colon) and having limited side effects due to an adapted fermentation kinetic.
The prebiotic activity has been defined by Gibson and Roberfroid in 1995 (Gibson G R and Roberfroid M, Dietary Modulation of the Human Colonic Microbiota: Introducing the Concept of Prebiotics, 1995) and revised in 2004 (Gibson G R, Probert H M, Loo J V, Rastall R A, Roberfroid M, Dietary Modulation of the Human Colonic Microbiota: Updating the Concept of Prebiotics), as “a selectively fermented ingredient that allows specific changes both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well being and health”. It has been shown previously that balancing the microbiota in favour of beneficial bacteria, like Bifidobacteria and Lactobacilli, and to the detriment of harmful bacteria, like coliforms or some species of clostridia, provides some health benefits. To reflect this prebiotic activity of an ingredient or food, a prebiotic index has been designed by Gibson and Roberfroid, taking into account the growth of Bifidobacteria and Lactobacilli as beneficial bacteria and coliforms and clostridia as negative bacteria.
Benefits of prebiotic substances include an improvement in mucosal barrier function, helping to prevent translocation of bacteria to the blood stream; the promotion of beneficial and reduction of pathogenic bacterial subpopulations; the production of short chain fatty acids (‘SCFAs’), especially propionate and butyrate, the major energy source for epithelial cells in the large intestine; SCFA also help to regulate sodium and water absorption; and an improvement in host immunity, via interactions between intestinal immune cells and pathogenic bacteria.
Some solutions have been suggested to get a high level of prebiotic effect. It has been proposed to incorporate prebiotic fibres with a high fermentation rate. Most recognised highly fermentable fibres are inulin and fructooligosaccharides (FOS) which have been extensively studied. However, most of the time fructooligosaccharides induce a rapid fermentation in the first part of the colon. This leads to some side effects like bloating, gas production and some social discomfort.
It has also been proposed to incorporate large amounts of prebiotic fibres with a medium fermentation rate. This could display desirable fermentation kinetics, but is generally an issue in terms of palatability and cost of the food products obtained. Moreover, it seems that there is also a saturation of the system when the fibre amount is too high. Finally, increasing the fibre content to high concentration can increase also the risk developing digestive discomfort.
KR20070076231 discloses a method of manufacturing a healthy food product comprising rice bran and buckwheat bran to produce an enhanced immune function, to reduce cholesterol, to regulate blood sugar and to treat and prevent diabetes.
“The combined uses of hull-less barley flour and xylanase as a strategy for wheat/hull-less barley flour and breads with increased arabinoxylan and 1-3,1-4 beta-D-glucan levels” Trogh et al, Journal of Cereal Science, discloses a bread made with a composite flour with 60% wheat flour and 40% hull-less barley flour.
“Maize bran/oat flour extruded breakfast cereal: a novel source of complex polysaccharides and an antioxidant” Holguin-acuna eta al., Food Chemistry, discloses a maize bran/oat flour extrude breakfast cereal.
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“Evaluation of baking procedures for incorporation of barley roller milling fractions containing high levels of dietary fibre into bread”, Jacobs et al., evaluates baking procedures for incorporating barley fractions containing high levels of dietary fiber into bread.